1. Field of the Invention
This invention relates generally to a produce washing system and, more particularly, to a produce washing system that employs a combination of bioelectrification energy and ultrasonic energy in a heated wash bath to remove or disable pathogens and other contaminants from the produce.
2. Discussion of the Related Art
The cleaning of produce to remove pathogens, including fungi, bacteria and viral forms, is increasingly important. After harvest, the exterior surface of produce is generally contaminated with fungicides and herbicides as a result of the growing process. Also, environmental pollutants, including various halogenated long-chain hydrocarbons and other synthetic chemical compounds, some of which are known to cause cancer in sufficiently concentrated forms, can sometimes be found on produce being shipped to the United States from foreign sources. Domestically grown produce, while sometimes better in terms of the overall level of contaminants, is still not free from synthetically produced chemicals resulting from herbicide and pesticide applications, from transportation and packaging, and from standard practices in the industry. Thus, it is desirable to have a washing system which provides cleaning of these undesirable pathogens, synthetic chemicals and non-naturally occurring substances from the produce prior to final shipment and sale to consumers.
Many produce cleaning procedures currently used in the industry only involve washing the produce in a water-based bath, or the like, to remove undesirable contaminants existing on the produce. Washing produce in water is limited in its ability to remove many pathogens and other contaminants, however. Therefore, more significant produce cleaning procedures have been proposed in the art.
U.S. Pat. No. 5,229,152 issued to Meldrum Jul. 20, 1993 discloses a process for extending the shelf life of produce, which includes immersing the produce in a snap freeze slurry that consists of by-products of the produce and certain sugars and acids. Prior to the produce being exposed to the snap-freeze slurry, it is immersed in a heated wash bath to remove dirt and other contaminants. The wash bath is subjected to ultrasonic sound waves to promote cleaning. The combination of the elevated temperature and mechanical vibration makes active and exposes the different micro-organisms which may exist on the produce.
Although the process of vibrating the wash bath at ultrasonic frequencies has been successful in removing pathogens and other contaminants from the produce, this produce washing process can be improved upon to further clean the produce and make it safer for human consumption.
Accordingly, it is an object of the present invention to create a higher quality washing system for produce, and a cleaner environment in which to handle produce.
It is another object of the present invention to provide an enhanced cleaning system using a multitude of forms of energy to help remove pathogens, synthetic chemicals, long dirt chains, as well as other contaminants.
In order to achieve this higher level of produce cleaning, the present invention proposes a washing system and process, according to a first aspect of the invention, that employs plural forms of energy in an ionic liquid-based washing system. The ionic liquid-based washing system includes solvents and solutes which promote the conduction of electrical energy. The electrical energy can be applied to the produce in various waveforms. The electrical energy in the various waveforms as described herein is generally referred to as bioelectrification. In addition, ultrasonic energy is employed to provide high-frequency mechanical pressure waves that agitate the produce to provide for the mechanical micromovement of the pathogens, dirt complexes, and other foreign substances on the surface of the produce.
The electrical energy and the mechanical energy combine to produce energy in the applicable resonant frequency range that acts to transform the pathogens, dirt and synthetic molecules so as to either destroy them or render them harmless. This breakdown of the pathogens and other constituents occurs both at the electrical level and the mechanical level. In addition, the electrical energy and/or mechanical energy promotes a decoupling of the harmful substances from the epithelial tissues of the produce. The harmful substances are put into solution and are ultimately carried away from the produce. The pathogens and other harmful substances in the solution may be removed by filtering, electrostatic precipitation, centrifugal action or any other desirable technique. In addition, the produce itself may simply be removed from the liquid bath, thus leaving pathogens behind. The produce may then be rinsed in a rinse tank or stabilization tank which helps further disassociate loose particles may still be clinging to the surface of the produce.
According to a second aspect of the invention, bio-electrification of liquid solvent/solute solutions containing the produce to be cleaned therein is used alone. In this particular preferred process, an alternating electrical energy source applies a current through a pair of opposed electrodes located on opposite sides of the tank to conduct electricity through the liquid medium which contains cations or anions to help conduct the electricity through the water-based solution. The electrical waveform can include a high frequency waveform modulated thereon to provide different levels of electrical resonance.
Additional objects, features and advantages of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.